"This all boils down to the headteacher. There are always going to be slight variations in trousers."

But it wasn't just females who were singled out.

One of the pupils included a boy who was told it made his private parts look "indecent".

The boy's friend's mum - Julie Abbott, 45, - said: "My son was allowed into school but one of his friends was told to go home and change.

"The reason given was that his trousers were too tight across his private parts and therefore it was indecent and not appropriate for school.

"These children are adolescents, going through all sorts of changes and coping with their hormones. It's outrageous to sexualise them in this way when all they have done is come to school wearing school uniform."